300tdi engine problems

replaced head gasket on my 300tdi auto 1996 as head gasket had gone . had head pressure tested and skimmed .used new head bolts and had mechanice come round to torque bolts down so i know it was done right . now heres the problem is only firing on front two cylinders at tick over when it gets to 2500 rpm then it runs fine . have checked valve clearances and are set at 0.20mm and are spot on and there is diesel flowing to the cylinders is rear two cylinders if you crack injectors makes no diffrence to engine note . where as if you crack front two engine tries to stall . drove landy up road realy slugish below 2500 rpm and white smoke the picks up after 2500 rpm and runs fine . didnt touck timing doing head and was running fine before changed gasket i used a 1.6mm gasket thickest they had when replacing head as is on last skim any ideas

Strange one. Since you've done the head skim, checked the valve clearances and checked the fuelling, the next thing would be to do a compression test. It could be a cracked block, or bent valve, but the compression test would indicate one of these problems.

did you replace the copper sealing washers on the bottom of the injectors?

right fess up time like an idiot i didnt mark up injector pipes when i took them off got 3 and 4 round wrong way ...................go on say it

Everybody makes mistakes.......You know what to do next time...M A R K THE PIPES B4 you take them off. I bet you never make that mistake again. LOL

In a similar vain...... taking the glo-plugs out on my disco today, what should I see, but a wraparound ident with "4" written on it, luckily on glo-plug #4.